Cancer encompasses a set of diseases having, in common, a disordered growth of cells that invade tissues and organs, and may spread to other regions of the body (metastasis). It is estimated that the number of individuals showing cancer manifestations will increase up to 55% until 2020 (Warren J L et al.: Current and Future Utilization of Services From Medical Oncologists, J Clin Oncol.; 26: 3242-3247, 2008).
The survival increase has turned cancer into a chronic disease, and subjected cancer patients to greater suffering. Suffering is caused by the tumor, other symptoms related to the disease, health damage caused by the treatment and emotional charge involving the diagnosis.
Among the most common symptoms, fatigue, pain, dyspnea, cognitive changes, loss of appetite, cachexia, nausea or depression can be cited.
Fatigue is particularly pointed out by patients with cancer as one of the most frequent symptoms present in all stages of the disease, as well as the prevailing and most debilitating symptom in people with advanced stage of cancer. Studies showed that approximately 40 to 80% of patients report fatigue during and after the treatment of disease (Hofman et al.: Cancer-related fatigue: the scale of the problem. Oncologist. 12 Suppl 1:4-10, 2007).
Mota et al. teaches that fatigue can be considered a subjective syndrome with multiple causes, whose onset and expression involve physical and psychic aspects (Mota et al.: Fadiga em pacientes com câncer avançado: conceito, avaliação e intervenção, Revista Brasileira de Cancerologia—Volume 48 n°4, 2002).
The word fatigue is also commonly used to describe a set of illnesses, from a generic state of lethargy to a specific heat sensation in the muscles caused by hardworking. Physiologically, this represents a decrease in overall capacity, which can be dangerous when tasks that require constant concentration carried out, such as driving a vehicle, since when a person is sufficiently fatigued, short periods of sleepiness may be experienced (concentration loss).
It is reported that the fatigue sensation originates in the reticular activating system at the base of the brain. Musculoskeletal structures would have co-evolved with appropriate brain structures so that the entire set works constructively and adaptively (Edelman, G. M. The remembered present: a biological theory of consciousness. Nova York: Basic Books, 1989).
However, despite of being frequent and debilitating, fatigue can be considered the symptom to which less effective interventions are known, especially when compared to those indicated for the control of other symptoms, like pain.
Thus, although the forms of fatigue control currently available include the use of pharmacological and non-pharmacological therapies, its management still represents a challenge (Giglio et al.: Fadiga relacionada ao câncer, Algoritmos, Einstein: Educ Contin Saúde. 2010;8(1 Pt 2): 44).
Accordingly, alternative therapies, with energy products, have been proposed. For example, guarana (Paullinia cupana), an Amazon shrub, is widely used in the manufacture of syrups, tablets, powders and soft drinks, and it is responsible, among others, for the stimulant effect able to increase resistance in mental and muscular efforts, reduce muscle and mental fatigue, especially in people without cancer. This ability is related to the presence of high dose of caffeine—about 2.5 to 5% (Weckerle et al.: Purine alkaloids in Paullinia. Phytochemistry. 2003;64(3):735-42.)
However, although the powder obtained from Paullinia cupana fruit is usually recommended, as a stimulant, for patients suffering from cancer, studies conducted with 75 mg in patients with cancer did not result in positive effects against fatigue (Miranda et. al: Guarana (Paullinia cupana) for chemotherapy-related fatigue, Study carried out at Serviço de Quimioterapia of Hospital Estadual Mário Covas—Santo André (SP), Brazil, Einstein. 2008; 6(2):195-9.)
Thus, there remains the need for an effective alternative for the treatment of fatigue, particularly fatigue related to cancer.